Grinding machine



Feb. 2,1943. J. E, PooRMAN 2,309,669 GRINDIVNG MACHINE Filed New.A 13, 1941 5 sheets-sheet 1 Feb. 2, 1943. J. E. PooRMAN 2,309,669

GRINDING MACHINE Filed Nov. 13, 1941 5 sheets-Sheena Feb. 2, 1943.-

J. E. PooRMAN GRINDING MACHINE Filed Nov. '13, 1941 5 sheets-sheet s Feb. 2, 1943, J. E. PoRMAN GRINDING MACHINE A Filed Nov. 13, 1941 5 sheets-sheet 4 Gttgrneg Patented Feb. 2, 1943 UNITED STATES PATENT OFFICE GRINDING MACHINE John E. Poorman, Philadelphia, Pa.y

Application November 13, 1941, Serial No. 418,979 21 Claims. (o1. 51e-231) This invention is directed to an improvement in grinding or like machines, with particular view of controlling the mechanism to insure absolute and desired precision in grinding operation.

In conventional grinding machines, it is customary to provide for automatic operation after the setting of the machine for the desired grinding. Thus in such conventional machines the table or other material base is set for a, predetermined limited movement for the desired grinding and during the nal step of this movement mechanism is set in motion to reverse the operation of the drive for the return of the table, and if desired, a further grinding during such return. Itnot infrequently happens that there is a variation in motion between the time the automatic reversing mechanism commences to operate and the completion of that operation, which variation is not infrequently due to inaccurate timing, wear of parts, or momentum over-run. Any such Variation is, of course, highly undesirable in any grinding operation and absolutely vital in precision grinding.

The primary object of the present invention is to insure an absolute predetermined stop for the movement of the table at the desired point, while at the same time permitting a control and operation of the table reversing mechanism, in order to insure that the cessation of the grinding operation can be positively controlled with extreme precision and provide that the reversing mechanism while set in motion incident to the stop of the table, may nevertheless proceed to carry out its reversing function without the possibility of any table movement, and therefore of any grinding, beyond the absolute predetermined limit.

The invention is illustrated in the accompanying drawings, in which Figure 1 is a front elevation of a grinding machine showing application of the invention.

Figure 2 is a transverse section substantially on line 2--2 of Figure 1.

v Figure 3 is a detail horizontal section on the line 3-3 of Figure 2.

Figure 4 is a detail inverted perspective view of the table of the grinding machine.

Figure 5 is a detailed section on the line 5-5 of Figure 4.

Figure 6 is a similar section on ythe line E-S of Figure 4.

Figure 7 is a detai1 section on the line 1-1 of Figure 6.

Figure 8 is a detail section on the line 8--8 of Figure 3.

Figure 9 is a detail section on the line 9 9 of Figure 3.

Figure 10 is a detail section on the line lil-ll] of Figure 3.

Figure 11 is a detail view of the gears and clutch means for reversing the motion of the gearing.

Figure 12 is a detail section of one ofthe stops and its mounting, the section being taken on the line I 2-l2 of Figure 1.

Figure 13 is a detail section on the line 13-13 of Figure l.

Figure 14 is a detail view showing the position of the stops at the moment of contact to stop the movement of the table at a predetermined point.

Figure 15 is'. a similar view but showing the stops positioned to stop movement of the table and actuate the reversing mechanism.

Figure 16 is a diagrammatic perspective View, illustrating the connections and coordination of parts incident to stopping the table at a predetermined point and at the same time permitting movement of the power operating means to reverse the movement of same, the parts being distorted to better illustrate the details.

Figure 17 is an enlarged front elevation of the mounting for one of the stops and its relation to the reversing lever.

Figure 18 is a central vertical section of same.

Figure 19 is an enlarged detail view of the handle and its connection with the table stop.

Figures 20 and 21 are diagrammatic sections showing the movement of the rack.

The grinding machine of the present invention is generally, aside from the details to be described, of more or less conventional form, and while it is necessary to describe some of such conventional parts for a complete understanding of the invention, it is to be understood that the invention is, with permissible mechanical changes, adapt-ed for any grinding machine of the type.

The machine comprises a main frame I of any appropriate structure on which is mounted a table 2 for receiving material to be operated on by the grinding mechanism, illustrated conventionally at 3. The grinding mechanism per se forms no particular part of the present invention, and may be of any appropriate type, such for example as shown in Patent No. 1,096,188, The lower surface of the table is formed near its rear edge vwith a V-shaped rib 4 to slidably seat -in a similarly-formed gudeway 5 in the frame. .The forward edge of the table has a bearing surface 6 to slide upon an appropriate surface area 1 of the frame. The table has a central longitudinal rib 8 thickened for the greater portion of its length and formed with a longitudinal channel 9 in which a rack I I is slidably mounted.

The rack II is held in sliding relation in the channel I through the medium of a plate I4 passing through an elongated slot I5 in the rack, with the plate terminally secured by blocks I6 fixed to the sides of the rib As will later appear, the movement of the rack bar independently of that of the table is very limited, and the slot I5 is of such length as to provide for the maximum of such movement. The rack bar I I has on its lower edge the usualgear teeth I1, t0 be driven as later described, and in its mounting the rack bar is constrained to form .in effect a rigid unit for moving the table 2 so long as the table movement is not interrupted by the set stops. In order to perform the desired functions, however, the rack bar must be capable of an independent movement after the table has been absolutely brought to rest, and to provide for this movement the following mechanism is provided. y

Depending from the rib 8 beyond and adjacent each end of the rack is an abutment I8 in each of which is mounted a threaded rod I9, adjustable relative to the rack through a nut 2l). Each end of the rack in line with the rod I9 is formed with a bore 2|, in which is slidably arranged a head 22 carried by a rod 23 extending through the end 24 of the bore and threaded to receive an adjusting nut 25 beyond the end of the bore. A spring 26 is interposed between the end 24 of the bore and the head 22, operating to urge the head toward and maintain it in contact with the end of the threaded rod |9. The rack inwardly of the bore 2| is formed with a through opening 21 to permit access to the nut 25 for adjusting the tension of the spring 26 and the position of the head 22.

It is to be particularly understood that the springs 26 at the respective ends of the rack II are of suicient rigidity to hold the rack fixed in relation to the table and compel the rack to operate the table as long as the table is free to move. but when the movement of the table is interrupted, as will later appear, the continued operation of the power will cause the rack to slide relative to the table in a selected direction through the yield of the springs 26.

Mounted on the forward face of the table is a hollow guide bar 28, the forward face of which has a reduced opening 29 throughout its length, and slidably mounted in this guide bar are space blocks 30. Each block has an extension projecting through and accurately fitting the opening 29, and to each extension is secured by bolts 30', a head 3| terminating at its lower end in a cylindrical formation 32, and at its upper end in a projection 33 of relatively reduced length.

Mounted in the cylindrical portion 32 of each head is a sleeve member 34 which extends in both directions beyond the cylindrical member 32. The sleeve members 34 are secured by set screws 35 to a longitudinally extending shaft 36 carried by an arm 31 secured to and projecting from the rack II. The sleeve member 34 within the cylinder 32 isof a diameter to provide' a space between its periphery and the inner periphery of the cylinder 32. This space is divided at the central portion by an annular projection 31 on the inner wall of the cylinder 32 and an outstanding projection 38 of washer form carried by the sleeve. The projections are in radial alignment but free of contact, and the washer 38 is preferably removable and bears against the shoulder integral with the sleeve in one direction and held in the other direction by a cylindrical liner 39 closely fitting the sleeve.

The space between the projections 31-38 is bridged by opposite washers 48, and springs 4| are provided in the space between the sleeve and the cylinder on opposite sides of the washers. The spring 4I at one end of the cylinder bears against the shoulder 42 formed in the sleeve and the spring 4I at the opposite end bears against the nut 43 threaded upon a section 44 of the sleeve which extends beyond the cylinder at the end opposite the set screw 35. If desired, the sleeve and nut 43 may be provided with annular extensions 45 to extend in the cylinder 32 and prevent buckling of the springs. From this construction, it will be apparent that the sleeve and block 3| are capable of relative movement axially of the shaft 36, with the movement resisted in any direction by a spring 4I in each cylinder. The upstanding projection 33 of the block 3| is provided with a stop 36', threaded through the projection 33, and adjustable longitudinally therein for setting purposes.

A frame support is secured to the frame I between the heads 32, this frame support being made up of spaced arms 41 secured to the frame, then extending upwardly as at 48 and then upwardly as at 49, terminating at the upper end in a plate 58. Swingingly supported at 5I on the plate 5|) is a stop bar 52, which is disposed accurately in line with the stops 35 carried by the heads 3|.

The reversing shaft 53, supported in bearings 54 in the frame I, is arranged between the arms 41 of the frame support. One end of the shaft is provided with reversing mechanism which will be hereinafter more particularly described. The forward end of the shaft is provided with a reversing lever 55, the lower end 56 of which depends between guards 51 to limit the swing of the lever. The upper end of the lever is provided with a stop 58 which is arranged in the path of and between the enlarged ends of the sleeves 34 in the cylinders 35.

The stop 58 is slidably mounted in the guide channel 59 in the reversing lever and provided with a pin 60 which extends through a slot 6I in one wall of the channel to permit vertical movement of the stop 58. As it is desirable at times to manually control the table stop 52 and the reversing stop 58, there is provided a bar 62, which at its lower end is connected by suitable means 63 to the pin 60 of the stop bar 58. The upper end of the rod 62 terminates in a head B4 slidable in a housing 63', which housing is provided with a handle 65. The housing 63 is, in effect, an extension of the stop 52. Thus, at will, the handle may be depressed to the limit of the movement of the head 64 in the housing 63 without affecting the rod 62, and as this movement of the handle will swing the stop 52, the stop 58 will not be 'correspondingly affected. If, however, it is desired to move both stops, appropriate depression of the handle 65 will swing the stop 52 out of its operative path and depress the stop 58 out of its operative path. When both stops are withdrawn from the path of the screws 40 and screws 34, it is necessary to disengage the power to prevent the table running o ff the frame. Means to prevent such disconnection will be hereinafter described.

The rack bar I I is driven by a pinion 69 xed on a stub shaft 51 mounted within the frame I and carrying a gear 68 in turn driven by a pinion 69 mounted upon the lower stub; shaft 10, which shaft carries a further gear 1|, meshing with a pinion 12 mounted upon a sleeve 13 rotating in a bearing carried by the frame I. The sleeve 'I3 is mounted on a shaft 14, on the terminal of which is keyed for sliding movement, a movable clutch member 15, the cooperating clutch member 16 of which is mounted upon a shaft11ilaligned with shaft dlsupported in a bearing 18 secured to the frame, which shaft 11 carries a bevel gear 19, driven by one or the other of gears 80-8I.

The bevel gear 19 cooperates through independently mounted frame bevel pinions 80 and 8|, loosely mounted onthe continuously driven unidirectional power shaft 83. 'Ihe pinions 80 and8l have clutch faces 84 and 85, between which a clutch element 86 is slidably keyed on the power shaft 83, such clutch element having a double clutch formation, to be operated as later described, and obviously serving to compel either selected pinion 80 or 8| to constitute the driving connection between the power shaft 83 and the bevel gear 19. It is, of course, apparent that driving function of one bevel pinion will reverse the direction of rotation of the bevel gear 19 as compared with the driving connection of the other bevel gear, and this while the power shaft 83 is continuously driven in one direction only,

It is, therefore, apparent that the movable clutch member 85 controls the reversal of the drive for the table 2, and also apparent that means must be provided for operating this clutch in the movement of the reversing shaft 53, and also for temporarily locking the clutch member in selected operative position.

To provide for this result a U-shaped frame member 81 is secured to the main frame, and its arms slidably support a shipper ro'd 88, extending toward and terminally provided with a shipper arm 89 cooperating in usual manner and .operable for shifting clutch member 8 6 in either direction for clutching function, under appropriate movement of the rod 88. The rod 88 is provided with Xed spaced blocks 90 and 9|. each having an upstanding lug 92. The reversing shaft 53 terminates adjacent the frame member 81 and has a rigidly connected terminal arm 93, pivotally connected at 94 to a shift lever 95 swingingly supported lat its lower end on theframe member 81. rThe shift lever has secured on one side near the upper end a swiveled sleeve 98 through ,which the shipper rod 88 freely slides.

Springs 91 and 98 encircle the rod 88 and bear respectively against the sleeve 95, lor interposed washers, and the respective blocks 90 and 9|. Locking levers 99 and |00 are swingingly supported on the arms of the frame member 81 and overlie, respectively, the rblocks 90 and 9|.

The levers are each provided with a tooth |I,

adapted where the parts are in position to close such lever 95 is in central or normal position. When the shift lever is moved in one direction or the other, the shoe |02 will engage beneath the locking lever 99 or |00 being approached and raise it to move its tooth |0| above possible cooperation with the lug 99 on the particular block 90 or 9|. Of course, it will be appreciated that the locking levers are free to gravitate to a position to cause engagement of the tooth of such levers with the lug 99 of the particular block 90 or 9|, when the parts are in proper position.

From the above, it will be apparent that the reversing shaft is being turned to move the shift lever 95 toward the left infFigure 1 to reverse the drive. It will be noted that the clutch member |15 has been previously set to provide drive in one direction, and that the tooth I0| of lever 99 is engaged with the lug 92 of block 90 to prevent movement of the shipper rod 88 in a direction to release the clutch. As the shift lever 95 moves toward the left, that is toward the locked block 90, it will iirst compress the spring 91 and then ride beneath and raise the locking lever 99. This releases the block 90, and causes the compressed spring 91 to instantly move the shipper rod 8-3 to shift the clutch member 86 to free clutch element and engage clutchelement 8d. This movement of the shipper rod 88, carries the block 9| to a position to cause the tooth 10| of locking lever |90 to drop behind the lug 92 of block 9|, and the clutch is temporarily locked in its new position, and the drive of the table is reversed. As the table moves in the new direction, the pressure of the-stop 3d on the reversinglever 55 is relieved, and the compressed spring 91 acts to l again center the shift lever 95, and through arm 93, reversing shaft 53, center the reversing lever 59. The reverse clutch operation is obvious, being identical with that described, except in direction of movement.

Provision is made for manually operating the rack and therefore the table as desired. To' this end a shaft |83 is mounted in the frame and carries at one end an arm |04 having conventional connection to the movable clutch element 15. The arm |04 has a pin |95 extending into a recess in the frame, and between the bottom of which recess and the arm a spring |08 is arranged to compel when free to act movement of the arm |84 in 'a direction to close the clutch. The end of the lshaft |03 remote from the arm |84 extends forwardly of the frame and is provided with a handle |01 formed with a cam end |08, which cam end cooperates with a cam |09 carried by the frame to cause movement of the handle |01 in one direction to shift the arm |99 against the tension of the spring |06 and open the clutch. Further turning of the handle |91 will obviously close the clutch through the spring |95.

The shaft 14 and sleeve 13 extend forwardly of the frame, and a handle member |10 is keyed to the sleeve and has a disc-like projection III encircling the sleeve. The shaft 10 is provided with a disc I|2 keyed to the shaft and connected to the disc ||l by ashear pin H3.

With the clutch 15 dis-connected, the pinion 12 and thereby the train of gear leading to the table may be turned to position the table in any desired position by the handle H0, acting through the discs ||I and ||2 and sleeve 13. With the clutch connected, the shaft 14 is driven by the power and in the event of undue interruption 4in any part of the drive or other detail mechanism, the pin |I3 will yield and be broken to disconnect the power from the pinion 'l2 and thereby from the train of gear leading to the table. This, of course, is a protective function.

As so far described, the operation of the mechanism is as follows. Under ordinary conditions as stated the springs 26 in the rack are suicient to prevent independent movement of the rack and table as the movement of the table is not interrupted. As the table moves the stop 52 will contact with one or the other of the stop screws 36 on the heads 3l. The movement of the table will be thus immediately stopped, and this stopping point can be determined with precision by appropriate adjustment of the stop screws 36. Of course, at this time one or the other of the stop screws 36 is in contact with the stop 52 and the table is stopped, but the rack bar, incident to the spring mechanism 26 previously described, is permitted to move under the continued operation of the power means. In this movement `of the rack bar l, the shaft 35 will, through its connection with the rack bar, move the particular sleeve member 34 in the direction of the rack bar movement and compelling the enlarged end of that sleeve member to engage the stop 58 and swing the reversing lever 55 to thereby partially turn the shaft 53 and actuate the automatic clutch mechanism previously described and move clutch member 85 to connect the appropriate pinion 80 or 8| in driving cooperation with the gear train to reverse the direction of the table.

Of course, under reversal of the table movement the springs 26 restore the relation of the table and rack, and the rack becomes in effect a xed part of the table for feeding it in the opposite direction.

Either stop 52 or stop 58, or both, may be moved out of operative relation to the control mechanism by means of the handle 65. When both stops are removed from the paths of the stop screws 36 and sleeve heads 34, and as previously stated, to prevent the table running off the frame, the lever 88 is operated to disconnect the power. Then the table is free to be manually reciprocated.

If it is desired to permit the table to be brought to rest at or about the time the automatic reversing mechanism is actuated, as in present conventional grinding machines, the stop 52 is removed from the path of movement of the stop screws 36', in which event the heads of the sleeves cooperate with the stop 58.

It will be apparent from the above description that the table may be stopped and the grinding effect upon the material carried by that table interrupted at any particular or desired point to insure complete and absolute precision in any grinding operation. It will be further evident that it is the interruption or stopping of the table which sets in operation the reversing mechanism, and that after the table is stopped, the power means in its continued movement will bring about an eiective reversal of its operative effect on the table without in any way permitting or influencing any table movement. Thus, regardless of wear of parts or dificulty in exact reversing period, the power means will still continue to bring into eiect its own reversal after a, complete cessation oi table movement, and without aiecting such table until complete reversal is effected.

What is claimed as new is:

1. A grinding apparatus including a material supporting table, a power train for operating the table in both directions, said train including a rack bar, reversing mechanism for the power means eiect on the table, means for stopping the movement of the table under the power means, and means inaugurated by the rack bar following cessation of table movement for actuating the reversing mechanism.

2. A grinding apparatus including' a material supporting table, a power train for operating the table in both directions, and including a rack bar means for stopping the table, the racl: bar being mounted for limited movement with respect to the table following cessation of table movement, reversing mechanism for the power means, and means inaugurated in the relatively independent movement of the rack bar for controlling the reversing means.

3. A grinding apparatus including a material supporting table, a, power train for operating the table in both directions, and including a rack bar, a connection between the rack bar and table to insure unit movement of the table and rack bar under the power means while the table is permitted to move, means for stopping the movement of the table, the connection between the rack bar and table permitting power means movement of the rack bar after the table is stopped, reversing mechanism for the power means, and connections to cause the rack bar in its movement independent of the table to operate the reversing mechanism.

4. In a, grinding apparatus, a material supporting table, power means for operating the table in both directions, a stop for stopping table movement, reversing mechanism for the power means, and an element of the power means for operating the table and mounted for independent movement with respect to the table after the table is stopped for actuating the reversing mechanism.

5. A construction as dened in claim 1 wherein auxiliary means are provided for effecting a reversal of table movement without interrupting the travel of the table.

6. A construction as defined in claim l wherein the means for actuating the reversing mechanism includes cooperating elements to temporarily lock the reversing mechanism in set position.

'7. A grinding apparatus including a material supporting table, a power train for operating the table in both directions including a rack bar, means for stopping the table, the rack bar being mounted for limited movement with respect to the table after the table movement is stopped, reversing mechanism for the power means, means inaugurated in the relatively independent movement of the rack bar for controlling the reversing means, and a secondary means selectively brought into operation for compelling operation of the reversing means by the rack bar without stopping table movement.

8. A construction defined in claim 7 wherein the means for controlling the reversing mechanism through the independent movement of the rack bar includes a reversing lever and stops responsive to the independent movement of the rack bar for actuating the lever.

9. A construction as dened in claim 7 wherein the secondarymeans for controlling the reversing mechanism includes a reversing lever and stops operated in the movement of the table to actuate said lever.

10. A construction as dened in claim 'l wherein the reversing mechanism includes a reversing lever and wherein the control of the reversing mechanism in the movement of the reversing lever incident to the relatively independent movement of the rack bar includes stops operated by the rack bar, and wherein the control of the reversing lever in the movement of the table includes secondary stops, the provision of means whereby the stops may be manually set in operative position or moved from such position.

11. A construction as defined in claim 1 wherein the power means may be manually disconnected from the table and wherein means are provided following such interruption to manually shift the table to any position desired.

12. In a grinding apparatus including a material supporting table, power means, a gear train between the power means and table for operating the table, means for stopping the table movement, means operated by the power means following stopping of table movement for reversing the effect of the power means on the table, manually operable means for disconnecting the table driving gear train from the power means, and manually operable means for actuating the gear train following such interruption.

13. A grinding apparatus, including a material supporting table, a, power train for operating the table in both directions, means for stopping the table at any predetermined point in its movement, means for reversing the power` train, and an element moving with and during the table movement under the power train and movable relative to the table by the power train when the table is stopped, and mechanism responsive to the relative movement of the element to operate the reversing means.

14. A construction as dened in claim 13, wherein the element is normally held in fixed relation to the table during table movement under the power train and is automatically and independently responsive to the power train for its relative movement when the table is stopped.

15. A construction as defined in claim 13, wherein the element is normally held in fixed relation to the table during table movement under the power train and is automatically and independently responsive to the power train for its relative movement when the table is stopped, the element being connected to the table by means maintaining normal relation of the element and table while the table is moving, said connecting means yielding to permit relative movement of the element under the power means when the table is stopped.

16. A grinding apparatus, including a material supporting table, power means therefor, a reversing mechanism for the power means, means for stopping the table movement, a table-moving element between the power means and table Cil having a normal relation to the table while the table is moving under the power means and capable of movement by the power means relative to the table when the table is stopped, and means to utilize such relative movement of the element to operate the reversing mechanism.

17. A construction as dened in claim 16, wherein the element is held in normal relation to the table by springs tensioned to permit relative movement of the element only when the table is stopped.

18. A construction as dened in claim 16, wherein the element is held in normal relation to the table by springs tensioned to permit relative movement of the element only when the table is stopped, said springs restoring normal relation of the element and table following operation of the reversing mechanism and consequent movement of the table.

19. A grinding apparatus, including a material supporting table, a power means therefor, a rack bar movable in the table and providing the operative connection between the power means and table, spring-means maintaining a normal relation between the table and rack bar and table while the table is moving under the power means, means for stopping the table movement at any predetermined point, said springs permitting movement of the rack bar under the power means when the table is stopped, and power means reversing mechanism operated by the relative movement of the rack bar.

20. A grinding apparatus, including a material supporting table, a power means therefor, a rack bar movable in the table and providing the operative connection between the power means and table, spring-means maintaining a normal relation between the table and rack bar and table while the table is moving under the power means, said spring means permitting relative movement of the rack bar under the power means when the table is stopped, adjustable stops for compelling complete cessation of table movement at any desired point in its path of travel, auxiliary stops carried by and movable relative to the adjustable stops, power means reversing mechanism, a movable element controlling such mechanism, and means operated by the relative movement of the rack bar to move the auxiliary stops to compel operation of the movable element to control the reversing mechanism.

21. A construction as defined in claim 20, wherein the adjustable stops are manually operable to a, position to avoid stopping the table movement, whereby the auxiliary stops will operate the reversing mechanism while the table is in motion.

JOHN E. POORMAN. 

